1. Field of the invention
The present invention relates to a process for joining elements in the manufacture of thermostructural composite material parts.
Thermostructural composite materials essentially comprise a fibrous reinforcement texture, substrate, or preform, comprising an arrangement of reinforcing fibers, densified by a matrix around the fibers. The fibers of the reinforcement texture and the matrix material are selected to satisfy applications requiring excellent mechanical characteristics at high temperatures. Typical examples of thermostructural composite materials include carbon-carbon materials (carbon fiber reinforcement texture and carbon matrix), carbon-ceramic (carbon fiber reinforcement structure and ceramic matrix, e.g. silicon carbide), and ceramic-ceramic (ceramic fiber reinforcement structure and ceramic matrix).
In some applications, especially in the space and aviation field, there is an ever-increasing need for large-size parts made of thermostructural composite materials. This is e.g. the case with stiffening web assemblies forming structural parts of a space vehicle.
2. Prior art
A large-size part could be produced from several separately produced parts that are finally assembled by mechanical means or gluing. However, known methods for assembling prefabricated elements made of thermostructural composite materials are difficult to put into practice, or do not give complete satisfaction.
One solution would consist in producing the elements of reinforcement texture separately, assembling them, possibly after a pre-densification step, and then providing a simultaneous densification by infiltration of the matrix material into the porosity of the reinforcement texture formed by the assembled elements of reinforcement texture. The elements of reinforcement texture are assembled simply by bringing them into mutual contact and holding them in contact by means of a tool. The linking between the elements of reinforcement texture results from the co-infiltration, or simultaneous infiltration, of the matrix material into the porous structure of these elements as they are held in contact. This co-infiltration can e.g. be obtained by means of a well-known method of chemical vapor deposition.
This type of linking by co-infiltration requires large contact surfaces to obtain an effective link by the matrix material, and presents a permanent risk of cohesion loss, both during manufacture and in use.